RRB NTPC - Averages (200 Questions with Explanation): Quantitative Aptitude Test

141.

The average of 26 numbers is zero. Of them, at the most how many may be greater than zero?

   A.) 25
   B.) 27
   C.) 24
   D.) 13

Answer: Option 'A'

Average of 26 numbers is = 0 Therefore sum of all 26 numbers = 0
It is quite possible that 25 of these numbers may be positive and if their sum is "a" then 26th number is "(-a)"

142.

There were 8 students in a particular Class. The class teacher knows the overall height of all the students in the class is 1200. Can you find the average height of students in the class?

   A.) 150
   B.) 155
   C.) 153
   D.) 159

Answer: Option 'A'

Use the below formula to find the average height of students in the class Average Height = ( Total Height of all students in the Class / Total Number of Students) Average Height = ( 1200/8) = 150

143.

A person's present age is two-fifth of the age of his mother. After 8 years, he will be one-half of the age of his mother. How old is the mother at present?   

   A.) 32 years
   B.) 36 years
   C.) 40 years
   D.) 48 years

Answer: Option 'C'

Let the mother's present age be x years.
Then, the person's present age =( 2 / 5years.)
After 8 years, he will be one-half of the age of his mother
=> ( 1 / 2) ( x + 8 )
=> ( 2 / 5 x + 8) = ( 1 / 2 ) ( x + 8)
=> 2( 2 x + 40) = 5 (x + 8)
=> 4 x + 80 = 5x + 40
=> 4x - 5x = 80 - 40
=> x = 40
Present age of Mother = 40 years.

144.

There were 8 students in a particular Class. The class teacher knows the overall height of all the students in the class is 1400. Can you find the average height of students in the class?

   A.) 192.5
   B.) 175
   C.) 183.75
   D.) 166.25

Answer: Option 'B'

Use the below formula to find the average height of students in the class Average Height = ( Total Height of all students in the Class / Total Number of Students) Average Height = ( 1400/8) = 175

145.

The average temperature for Monday, Tuesday and Wednesday was 41 c. the average temperature for Tuesday, Wednesday and Thursday was 42 c. If the temperature on Thursday be 43 c, what was the temperature on Monday?

   A.) 41 c
   B.) 39 c
   C.) 40 c
   D.) 42 c

Answer: Option 'C'

Answer: Option 'C'

146.

A man spends Rs. 1600 per month on an average for the first three months, Rs 1550 for next four months and Rs. 1800 per month for the last five months and saves Rs . 5200 a year. What is his average monthly income (in Rs.)?

   A.) 2510
   B.) 2100
   C.) 2684
   D.) 2110

Answer: Option 'B'

Total expenditure for the first 3 months = 3 × 1600 = 4800
Total expenditure for 4 months = 4 × 1550 = 6200
Total expenditure for 5 months = 5 × 1800 = 9000
Total expenditure and saving (which is income for one year) = 4800 + 6200 + 9000 + 5200 = Rs. 25200
So, Average monthly income = 25200/12 = Rs. 2100

147.

The average of 24 numbers is zero. Of them, at the most how many may be greater than zero? 

   A.) 20
   B.) 21
   C.) 22
   D.) 23

Answer: Option 'D'

Average of 24 numbers is = 0
Therefore sum of all 24 numbers = 0
It is quite possible that 23 of these numbers may be positive and if their sum is "a" then 24th number is "(-a)"

148.

There were 8 students in a particular Class. The class teacher knows the overall height of all the students in the class is 1200. Can you find the average height of students in the class?

   A.) 150
   B.) 155
   C.) 153
   D.) 159

Answer: Option 'A'

Use the below formula to find the average height of students in the class Average Height = ( Total Height of all students in the Class / Total Number of Students) Average Height = ( 1200/8) = 150

149.

Total Marks obtained by a class is 1564 and the average score of the class is 68. Find the Total students in the class? 

   A.) 21
   B.) 22
   C.) 23
   D.) 24

Answer: Option 'C'

Use the below formula to find the Total,
when Average and Total No. of Students is provided
Total no of students = Total Marks / Average Marks 
Total No. of students = ( 1564 / 68) = 23.

150.

Father is aged three times more than his son Ronit. After 8 years, he would be two and a half times of Ronit's age. After further 8 years, how many times would he be of Ronit's age ? 

   A.) 2 3/4 times
   B.) 2 times
   C.) 2 1/2 times
   D.) 3 times

Answer: Option 'B'

Let Ronit's present age be x years.
Then, father's present age =(x + 3x) years = 4x years.
Therefore, (4x + 8) = 5/2 (x + 8 )
=> 8x + 16 = 5x + 40
=> 3x = 24
=> x = 8.
Hence, required ratio = (4x + 16)/ (x + 16 )
= 48 / 24 = 2 .

151.

Total Marks obtained by a class is 1632 and the average score of the class is 68. Find the Total students in the class? 

   A.) 22
   B.) 24
   C.) 26
   D.) 28

Answer: Option 'B'

Use the below formula to find the Total, when Average and Total No. of Students is provided.
Formula: Total no of students = Total Marks / Average Marks
Total No. of students = ( 1632 / 68) = 24

152.

The average temperature for Monday, Tuesday and Wednesday is 36.30 C. The average temperature for Tuesday, Wednesday and Thursday is 36.70 C. If Monday's temperature recorded as 390 C, find the Thursday's temperature ?

   A.) 40.2º C
   B.) 40.4º C
   C.) 40.5º C
   D.) 41.2º C

Answer: Option 'A'

Mon + Tue + Wed Temperature = 3X36.3 = 108.9
Given, Monday's temperature = 39º C
=> Tue + wed Temperature = 108.9 - 39 = 69.9
Given, Tue + wed + Thu temperature = 3 X 36.7 = 110.1
So, Thursday's temperature = 110.1 - 69.9 = 40.2º C

153.

Total Marks obtained by a class is 3685 and the average score of the class is 55. Find the Total students in the class?

   A.) 65
   B.) 66
   C.) 67
   D.) 68

Answer: Option 'C'

Use the below formula to find the Total, when Average and Total No. of Students is provided Total no of students = Total Marks / Average Marks Total No. of students = ( 3685 / 55) = 67

154.

Of three numbers, the third is twice the second and the second is 4 times the first. If their average is 78, the smallest of the three numbers is: 

   A.) 15
   B.) 21
   C.) 17
   D.) 18

Answer: Option 'D'

Let first number be x. 
So,2nd no. = 4x & 3rd no.=8x.
So,x+4x+8x=78 × 3 = 234.
13x = 234 
x = 234/13 
Hence,smallest Number x=18.

155.

The average weight of a class having 16 students is 36 kg. Find the total weight of the class.

   A.) 576
   B.) 556
   C.) 496
   D.) 526

Answer: Option 'A'

Solution is
Given :
Average weight of a class having 16 students is 36 kg
Average = Total Quantity / No. of Quantity
Total quantity = Avg x No. of Quantity

Total quantity = 16 x 36 = 576
Answer is 576

156.

Average of 13 results is 65. If the average of first six results is 61 and average of last six results is 59. Then find the seventh result? 

   A.) 135
   B.) 125
   C.) 115
   D.) 105

Answer: Option 'B'

Given,Average of 13 results is 65.
Total result = Average * No. of results
=> Total result = 13 x 65 = 845
Given,average of first six results = 61
=> Total of first six = 61 * 6 = 366 and
Given,average of last six results is 59
=> Total for last six = 59 * 6 = 354
Then,
Seventh result = Total result – (Total of first six + Total for last six)
= 845 - ( 366 + 354 )
= 125
Therfore, Seventh result = 125

157.

The average of 14 numbers is zero. Of them, at the most how many may be greater than zero ?

   A.) 14
   B.) 13
   C.) 12
   D.) 7

Answer: Option 'B'

Average of 14 numbers is = 0
Therefore sum of all 14 numbers = 0
It is quite possible that 13 of these numbers may be positive and if their sum is "a" then 14th number is "(-a)"

158.

A particular student has scored an average marks of 69.25 in all his 43 subjects. Find the Total Score he has obtained in all his subjects?

   A.) 3275.53
   B.) 3126.64
   C.) 2977.75
   D.) 2828.86

Answer: Option 'C'

Use the below formula to find the Total, when Average and Total No. of Students is provided Total = Average * Total Students/People Total = Average * Total Number of Students) Average Weight = ( 69.25 x 43) = 2977.75

159.

In the first 10 overs of a cricket game, the run rate was only 8.2. What should be the run rate in the remaining 40 overs to reach the target of 106 runs?

   A.) 0.66
   B.) 0.6
   C.) 0.82
   D.) 0.54

Answer: Option 'B'

Required Run rate = ( 106 - ( 8.2 x 10 ) )/ (40) = ( 24) /(40) = 0.6

160.

The average age of a group of 10 students was 22. The average age increased by 1 years when two new students joined the group. What is the average age of the two new students who joined the group?

   A.) 28
   B.) 28.7
   C.) 30
   D.) 32

Answer: Option 'A'

The average age of a group of 10 students is 22.
Therefore, the sum of the ages of all 10 of them = 10 * 22 = 220
When two students joins the group, the average increase by 1. New Average = 23
Now there are 12 students Therefore, sum of all the ages of 12 students = 12 x 23 = 276
Therefore, the sum of the ages of two students who joined = 276 - 220 = 56
And the average age of these two students = 28


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